1. Field of the Invention
The invention relates to a ground clip for a computer system board and, more particularly, to a ground clip which supportably mounts a computer system board above a computer system chassis base.
The invention further relates to a method for installing a grounded printed circuit board in a computer system chassis and, more particularly, to a method for installing a supportably grounded, slideably mountable printed circuit board in a computer system chassis.
2. Description of Related Art
A computer system typically includes at least one computer system board mounted within a protective chassis formed of a hardened material such as steel. Most commonly, a computer system board which is mounted within a protective chassis is comprised of a plurality of electronic components having multiple pin connectors mounted on an underlying substrate which provides interconnections between the connector pins of the various electronic components. As most electronic components typically include at least one connector pin which must be connected to ground, providing a conductive path from each electronic component to ground has long been an important concern in designing computer system boards. As the protective chassis within which the computer system board is typically mounted is often utilized as the ground for the computer system board and its components, it is often necessary to furnish a conductive path from the computer system board to the protective chassis. Most commonly, the computer system board is provided with a ground point that is electrically connected to the electrical components requiring a path to ground. The ground point is then electrically connected to the chassis. However, because of the high density of electrical components mounted on a typical computer system board, most computer system boards require more than one independent grounding point to fully satisfy the board's grounding needs. As a result, multiple electrical connections between the computer system board and the chassis are often required.
In addition to grounding requirements, computer system boards also demand support and mounting requirements. In most computer systems, the computer system board is supportably mounted directly above the chassis in order to optimize grounding connections and flexibility. However, because the electrical components mounted on the computer system board utilize the chassis as a ground, direct contact between the chassis and the electrical components must be avoided, as such contact could create a short-to-ground for the electrical components. The mounted system board, therefore, must be firmly secured above the chassis, since any excessive vibration that allows the board to contact the chassis could create a short circuit and potentially inflict irreparable harm to the board and its components. Finally, it is advantageous if the board is configured such that the installation and/or removal of the board may be completed without disrupting other components within the computer chassis. It is well understood by service personnel that limiting access and removal of the system board can create problems during field repair.
While prior ground clips satisfactorily provided a path from the electrical components to ground, such ground clips failed to provide mechanical support sufficient to maintain the board above the chassis. Furthermore, such prior clips were not configured to promote the slideable installation of the board. For example, in a "unit-to-unit" ground, a system board is inserted into a docking bay wherein a grounding contact between the two is formed. The unit-to-unit ground, however, fails to provide any shock or vibration protection for the system board. The required stability can only be accomplished by additionally fastening the board to the chassis.
Support of the system board has been addressed separately. Presently, many computer systems are provided with posts or premounted standoffs for supporting and securing the system board above the chassis. Most commonly, these standoffs are formed as vertically oriented chassis projections which engage the bottom of the system board. The system board is provided with corresponding apertures positioned directly above the standoff so that the board may be screw mounted to the standoff. While the use of standoffs securely mounts the system board to the chassis, their use is not particularly well suited for many applications. In particular, standoffs severely limit flexibility in designing the system board. Specific board locations must be selected and dedicated for a series of screw mounting apertures which correspond to the standoff locations on the chassis. Once selected, the aperture locations may not be modified without modifying the chassis as well. As a result, the exchangeability between system boards and chassis are hindered because the screw mounting holes and standoffs for the system board/chassis configuration for a first computer system are usually provided in different locations than the screw mounting holes and standoffs for the system board/chassis configuration of a second computer system. A separate chassis, therefore, must be manufactured for each type of system board such that the chassis standoffs correspond to the mounting holes on the boards. Furthermore, because of their locational inflexibility, the standoffs are sometimes not suitable for functioning as the only grounding connection for the system board. Accordingly, separate grounding connections must be provided. Finally, due to the rigid construction of the standoffs, the system board can only be lowered onto the standoffs. Laterally sliding the system board into a predesignated slot would likely result in damage or removal of the electrical components or circuitry on the under-side of the board.